Rapid Assessment of Avoidable Blindness in India

BACKGROUND: Rapid assessment of avoidable blindness provides valid estimates in a short period of time to assess the magnitude and causes of avoidable blindness. The study determined magnitude and causes of avoidable blindness in India in 2007 among the 50+ population. METHODS AND FINDINGS: Sixteen randomly selected districts where blindness surveys were undertaken 7 to 10 years earlier were identified for a follow up survey. Stratified cluster sampling was used and 25 clusters (20 rural and 5 urban) were randomly picked in each district.. After a random start, 100 individuals aged 50+ were enumerated and examined sequentially in each cluster. All those with presenting vision = 50 years were enumerated, and 94.7% examined. Based on presenting vision,, 4.4% (95% Confidence Interval[CI]: 4.1,4.8) were severely visually impaired (vision<6/60 to 3/60 in the better eye) and 3.6% (95% CI: 3.3,3.9) were blind (vision<3/60 in the better eye). Prevalence of low vision (<6/18 to 6/60 in the better eye) was 16.8% (95% CI: 16.0,17.5). Prevalence of blindness and severe visual impairment (<6/60 in the better eye) was higher among rural residents (8.2%; 95% CI: 7.9,8.6) compared to urban (7.1%; 95% CI: 5.0, 9.2), among females (9.2%; 95% CI: 8.6,9.8) compared to males (6.5%; 95% CI: 6.0,7.1) and people above 70 years (20.6%; 95% CI: 19.1,22.0) compared to people aged 50-54 years (1.3%; 95% CI: 1.1,1.6). Of all blindness, 88.2% was avoidable. of which 81.9% was due to cataract and 7.1% to uncorrected refractive errors/uncorrected aphakia. CONCLUSIONS: Cataract and refractive errors are major causes of blindness and low vision and control strategies should prioritize them. Most blindness and low vision burden is avoidable

Interactions of Ar(9+) and metastable Ar(8+) with a Si(100) surface at velocities near the image acceleration limit

Auger LMM spectra and preliminary model simulations of Ar(9+) and metastable Ar(8+) ions interacting with a clean monocrystalline n-doped Si(100) surface are presented. By varying the experimental parameters, several yet undiscovered spectroscopic features have been observed providing valuable hints for the development of an adequate interaction model. On our apparatus the ion beam energy can be lowered to almost mere image charge attraction. High data acquisition rates could still be maintained yielding an unprecedented statistical quality of the Auger spectra.Comment: 34 pages, 11 figures, http://pikp28.uni-muenster.de/~ducree

Extended Classical Over-Barrier Model for Collisions of Highly Charged Ions with Conducting and Insulating Surfaces

We have extended the classical over-barrier model to simulate the neutralization dynamics of highly charged ions interacting under grazing incidence with conducting and insulating surfaces. Our calculations are based on simple model rates for resonant and Auger transitions. We include effects caused by the dielectric response of the target and, for insulators, localized surface charges. Characteristic deviations regarding the charge transfer processes from conducting and insulating targets to the ion are discussed. We find good agreement with previously published experimental data for the image energy gain of a variety of highly charged ions impinging on Au, Al, LiF and KI crystals.Comment: 32 pages http://pikp28.uni-muenster.de/~ducree

Fluorescent Cell Barcoding as a Tool to Assess the Age-Related Development of Intracellular Cytokine Production in Small Amounts of Blood from Infants

Fluorescent Cell Barcoding (FCB) is a flow cytometric technique which has been used for assessing signaling proteins. This FCB technique has the potential to be applied in other multiparameter analyses. Since data on antigen (Ag)-specific T-cell immune responses, like intracellular cytokine production, are still lacking in infants because limited blood volumes can be obtained for analysis, the FCB technique could be very useful for this purpose. The objectives of this study were to modify the FCB method to be able to measure multiple Ag-specific cytokine reponses in T-cells upon simultaneous stimulation by various antigens and mitogens in small amounts of blood and to investigate the cytokine pattern of T-cell subsets in healthy infants aged six and twelve months. Blood samples, collected from 20 healthy infants aged six and twelve months, were stimulated in vitro with the antigens: phorbol-myristate-acetate (PMA), purified-protein-derivative (PPD), Tetanus-toxoid (TT), Staphylococcal-enterotoxin-B (SEB), and phytohemagglutinin (PHA). Each stimulus was barcoded by labelling with different intensities of fluorescent cell barcoding (FCB) markers. Intracellular production of interleukin-2, interferon-gamma, and tumor necrosis factor-alpha was measured simultaneously in just one blood sample of 600 µl whole blood. Significant age-related differences in cytokine production were shown for PMA, PHA, and TT in CD4+ T-cells, and for PMA, PHA, SEB, and TT in CD8+ T-cells. The intracellular cytokine production by CD4+ and CD8+ T-cells was higher at twelve months compared to six months of age for all antigens, except for PMA, which was lower at the age of twelve months. Based on the consistency in both T-cell subsets, we conclude that the new FCB method is a promising tool to investigate the age-related development of intracellular cytokine production in infants

Rapid assessment of visual impairment (RAVI) in marine fishing communities in South India - study protocol and main findings

<p>Abstract</p> <p>Background</p> <p>Reliable data are a pre-requisite for planning eye care services. Though conventional cross sectional studies provide reliable information, they are resource intensive. A novel rapid assessment method was used to investigate the prevalence and causes of visual impairment and presbyopia in subjects aged 40 years and older. This paper describes the detailed methodology and study procedures of Rapid Assessment of Visual Impairment (RAVI) project.</p> <p>Methods</p> <p>A population-based cross-sectional study was conducted using cluster random sampling in the coastal region of Prakasam district of Andhra Pradesh in India, predominantly inhabited by fishing communities. Unaided, aided and pinhole visual acuity (VA) was assessed using a Snellen chart at a distance of 6 meters. The VA was re-assessed using a pinhole, if VA was < 6/12 in either eye. Near vision was assessed using N notation chart binocularly. Visual impairment was defined as presenting VA < 6/18 in the better eye. Presbyopia is defined as binocular near vision worse than N8 in subjects with binocular distance VA of 6/18 or better.</p> <p>Results</p> <p>The data collection was completed in <12 weeks using two teams each consisting of one paramedical ophthalmic personnel and two community eye health workers. The prevalence of visual impairment was 30% (95% CI, 27.6-32.2). This included 111 (7.1%; 95% CI, 5.8-8.4) individuals with blindness. Cataract was the leading cause of visual impairment followed by uncorrected refractive errors. The prevalence of blindness according to WHO definition (presenting VA < 3/60 in the better eye) was 2.7% (95% CI, 1.9-3.5).</p> <p>Conclusion</p> <p>There is a high prevalence of visual impairment in marine fishing communities in Prakasam district in India. The data from this rapid assessment survey can now be used as a baseline to start eye care services in this region. The rapid assessment methodology (RAVI) reported in this paper is robust, quick and has the potential to be replicated in other areas.</p